Rather surprised not to have seen this story crop up on here yet:
https://www.aerotime.aero/articles/3...ht-to-bulgaria
An unidentified [Piper PA-23–250-Aztec] with its transponder and radio turned off flew [from Lithuania through] the airspaces of Hungary, Romania, Serbia and Bulgaria on June 8, 2022.
The occupants had disappeared from the plane, which landed at a disused airfield, by the time the authorities got there.
This reads like the plot of John Le Carré novel (specifically,
The Honourable Schoolboy - the plane was even misidentified as a Beechcraft at first!).
Is this kind of event common? Is it in effect relatively easy to wander around European airspace anonymously in a light aircraft without being bothered?